Question 1

Which of the following statements concerning entropy is not correct?

Accepted Answer

A)   The entropy of a system increases as the number of available microstates increases.
B)   The entropy of a system is proportional to the natural log of the number of microstates.
C)   In a spontaneous process,ΔS(universe) indicates the extent to which energy is dispersed.
D)   The dispersal of matter,such as the spontaneous expansion of a gas,cannot be explained by an increase in entropy.
E)   Entropy is a measure of the extent of energy dispersal.F) B) and D)
G) A) and D)

Question 2

Calculate ΔrG° for the reaction below at 425 °C, 2 HI(g)  rG° for the reaction below at 425 °C, 2 HI(g)    H2(g) + I2(g) ; K = 0.018.(R = 8.314 J/K⋅mol)  A)  6.12 × 103 kJ/mol-rxn B)  1.05 × 104 kJ/mol-rxn C)  1.42 × 104 kJ/mol-rxn D)  2.33 × 104 kJ/mol-rxn E)  3.34 × 105 kJ/mol-rxn" class="answers-bank-image d-inline" rel="preload" > H2(g) + I2(g) ; K = 0.018.(R = 8.314 J/K⋅mol)

Accepted Answer

A)   6.12 × 103 kJ/mol-rxn
B)   1.05 × 104 kJ/mol-rxn
C)   1.42 × 104 kJ/mol-rxn
D)   2.33 × 104 kJ/mol-rxn
E)   3.34 × 105 kJ/mol-rxnF) A) and E)
G) A) and D)

Question 3

What is the equilibrium constant for reaction below at 25 °C? (R = 8.314 J/K⋅mol)  2 NO(g) + O2(g)  2(g)    2 NO2(g) ; ΔfG° [NO(g) ] = +86.6 kJ/mol and ΔfG° [NO2(g) ] = +51.2 kJ/mol. A)  3.9 × 10-13 B)  1.0 × 10-11 C)  2.6 × 1012 D)  1.6 × 106 E)  3.8 × 1028" class="answers-bank-image d-inline" rel="preload" > 2 NO2(g) ; ΔfG° [NO(g) ] = +86.6 kJ/mol and ΔfG° [NO2(g) ] = +51.2 kJ/mol.

Accepted Answer

A)   3.9 × 10-13
B)   1.0 × 10-11
C)   2.6 × 1012
D)   1.6 × 106
E)   3.8 × 1028F) B) and D)
G) A) and B)

Question 4

Using the given data,determine ΔrG° at 500.0 K for the reaction below. Ba(s) + H2O(g) → BaO(s) + H2(g) 
Substance
ΔfH°(kJ/mol-rxn) at 298 K
S° (J/K·mol-rxn) at 298 K
Ba(s) 
0
62) 8
H2O(g) 
-241.8
188) 7
BaO(s) 
-592
70) 4
H2(g) 
0
130) 6

Accepted Answer

A)   325.0 kJ/mol-rxn
B)   -325.0 kJ/mol-rxn
C)   335.2 kJ/mol-rxn
D)   -335.2 kJ/mol-rxn
E)   -375.5 kJ/mol-rxnF) A) and D)
G) B) and D)

Question 5

Which of the following relationships is not true?

Accepted Answer

A)   
B)   
C)   
D)   
E)   F) All of the above
G) A) and B)

Question 6

Which of the following changes lead to a decrease in entropy?

Accepted Answer

A)   Sugar dissolving in coffee
B)   Diffusion of perfume throughout a room
C)   Evaporation of gasoline
D)   The sublimation (vaporization) of dry ice (solid carbon dioxide) 
E)   Condensation of steam on glassF) D) and E)
G) B) and E)

Question 7

For a reaction,ΔrH° = -208.8 kJ and ΔrS° = -308.2 J/K.At what temperature will ΔrG° = 0.00 kJ?

Accepted Answer

A)   0.68 K
B)   677.5 K
C)   1476 K
D)   6435 K
E)   0.85 KF) A) and E)
G) A) and D)

Question 8

At what temperatures will a reaction be spontaneous if ΔrH° = +62.4 kJ and ΔrS° = +301 J/K?

Accepted Answer

A)   All temperatures below 207 K
B)   All temperatures above 207 K
C)   Temperatures between 179 K and 235 K
D)   The reaction will be spontaneous at any temperature
E)   The reaction will never be spontaneousF) A) and D)
G) C) and D)

Question 9

The total entropy of the universe is always increasing.This is a statement of the _____ law of thermodynamics.

Accepted Answer

The answer of The total entropy of the universe is...

Question 10

Which of the following is true of a reaction that is product-favored?

Accepted Answer

A)   Q rG rG > 0 
C)   Q = K and   rG = 0 
D)   Q > K and   rG  K and   rG > 0" class="answers-bank-image d-inline" rel="preload" > rG 
B)   Q rG rG > 0 
C)   Q = K and   rG = 0 
D)   Q > K and   rG  K and   rG > 0" class="answers-bank-image d-inline" rel="preload" > rG > 0
C)   Q = K and rG rG > 0 
C)   Q = K and   rG = 0 
D)   Q > K and   rG  K and   rG > 0" class="answers-bank-image d-inline" rel="preload" > rG = 0
D)   Q > K and rG rG > 0 
C)   Q = K and   rG = 0 
D)   Q > K and   rG  K and   rG > 0" class="answers-bank-image d-inline" rel="preload" > rG 
E)   Q > K and rG rG > 0 
C)   Q = K and   rG = 0 
D)   Q > K and   rG  K and   rG > 0" class="answers-bank-image d-inline" rel="preload" > rG > 0F) All of the above
G) B) and D)

Question 11

For which of the following substances is the standard free energy of formation not equal to zero at 298 K?

Accepted Answer

A)   Xe(g) 
B)   Sn(s) 
C)   N2(g) 
D)   Mg(g) 
E)   Mn(s) F) A) and B)
G) None of the above

Question 12

For the reaction given below,ΔH0 = −1516 kJ at 25°C and ΔS0 = −432.8 J/K at 25°C.This reaction is spontaneous _____. SiH4(g) + 2 O2(g) → SiO2(s) + 2 H2O 0 = −1516 kJ at 25°C and ΔS0 = −432.8 J/K at 25°C.This reaction is spontaneous _____. SiH4(g) + 2 O2(g) → SiO2(s) + 2 H2O   A)  only below a certain temperature B)  only above a certain temperature C)  at all temperatures D)  only when entropy is zero E)  None of these" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   only below a certain temperature
B)   only above a certain temperature
C)   at all temperatures
D)   only when entropy is zero
E)   None of theseF) C) and E)
G) A) and E)

Question 13

For a certain reversible process,q = 88.06 kJ at 29.4°C.Which of the following is the ΔS for the process?

Accepted Answer

A)   0.291 J/K
B)   291 J/K
C)   3.00 J/K
D)   -0.291 J/K
E)   2590 J/KF) B) and C)
G) C) and E)

Question 14

A reaction is said to be under thermodynamic control when _____.

Accepted Answer

A)   thermodynamics is controlling the ratio of products
B)   the ratio of products is the same at all temperatures
C)   thermodynamics is controlling the speed of the reaction
D)   the ratio of reactants is equal to the ratio of products
E)   there are both acidic and basic reactants in a reactionF) A) and D)
G) B) and E)

Question 15

If a chemical reaction is exothermic but not spontaneous,which of the following must be true?

Accepted Answer

A)   ΔrG > 0,ΔrS > 0,and ΔrH > 0
B)   ΔrG rS > 0,and ΔrH > 0
C)   ΔrG > 0,ΔrS rH > 0
D)   ΔrG rS rH 
E)   ΔrG > 0,ΔrS rH < 0F) A) and D)
G) A) and B)

Question 16

While diluting concentrated sulfuric acid with water,the temperature of the solution increases rapidly.What are the signs of ΔrH,ΔrS,and ΔrG for the process?

Accepted Answer

A)   ΔrH rS > 0,and ΔrG 
B)   ΔrH rS rG 
C)   ΔrH rS > 0,and ΔrG > 0
D)   ΔrH > 0,ΔrS > 0,and ΔrG 
E)   ΔrH > 0,ΔrS rG > 0F) A) and B)
G) A) and E)

Question 17

Which of the following compounds has the highest standard entropy per mole at 298 K?

Accepted Answer

A)   H2O(l) 
B)   CaCO3(s) 
C)   CO(g) 
D)   SiO2(s) 
E)   CH3OH(l) F) B) and D)
G) B) and E)

Question 18

Which of the following is the third law of thermodynamics as defined by Ludwig Boltzmann?

Accepted Answer

A)   A perfect crystal at 0 K has zero entropy.
B)   In a spontaneous process,the entropy of the universe increases.
C)   The total entropy of the universe is always increasing.
D)   The total mass of the universe is constant.
E)   Mass and energy are conserved in all chemical reactions.F) A) and E)
G) C) and E)

Question 19

For the reaction Br2(l) → 2Br(g) ,_____.

Accepted Answer

A)   ΔH is + and ΔS is +
B)   ΔH is + and ΔS = 0
C)   ΔH is - and ΔS is -
D)   ΔH is - and ΔS is +
E)   ΔH is + and ΔS is -F) All of the above
G) A) and D)

Question 20

ΔG° = 0 for a reaction indicates that _____.

Accepted Answer

A)   the reaction favors formation of products
B)   the reaction is at equilibrium
C)   the reaction is nonspontaneous
D)   the reaction is spontaneous
E)   the reaction cannot reach equilibriumF) A) and B)
G) A) and C)

Exam 19: Principles of Chemical Reactivity: Entropy and Free Energy

A reaction is said to be under thermodynamic control when _____.

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For the reaction Br2(l) → 2Br(g) ,_____.

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The total entropy of the universe is always increasing.This is a statement of the _____ law of thermodynamics.

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At what temperatures will a reaction be spontaneous if ΔrH° = +62.4 kJ and ΔrS° = +301 J/K?

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For the reaction given below,ΔH0 = −1516 kJ at 25°C and ΔS0 = −432.8 J/K at 25°C.This reaction is spontaneous _____. SiH4(g) + 2 O2(g) → SiO2(s) + 2 H2O

Correct AnswerverifiedShow Answer

For a certain reversible process,q = 88.06 kJ at 29.4°C.Which of the following is the ΔS for the process?

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What is the equilibrium constant for reaction below at 25 °C? (R = 8.314 J/K⋅mol) 2 NO(g) + O2(g) 2 NO2(g) ; ΔfG° [NO(g) ] = +86.6 kJ/mol and ΔfG° [NO2(g) ] = +51.2 kJ/mol.

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While diluting concentrated sulfuric acid with water,the temperature of the solution increases rapidly.What are the signs of ΔrH,ΔrS,and ΔrG for the process?

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Which of the following statements concerning entropy is not correct?

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Which of the following is true of a reaction that is product-favored?

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Which of the following relationships is not true?

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Using the given data,determine ΔrG° at 500.0 K for the reaction below. Ba(s) + H2O(g) → BaO(s) + H2(g) Substance ΔfH°(kJ/mol-rxn) at 298 K S° (J/K·mol-rxn) at 298 K Ba(s) 0 62) 8 H2O(g) -241.8 188) 7 BaO(s) -592 70) 4 H2(g) 0 130) 6

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Which of the following compounds has the highest standard entropy per mole at 298 K?

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Which of the following changes lead to a decrease in entropy?

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Which of the following is the third law of thermodynamics as defined by Ludwig Boltzmann?

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For which of the following substances is the standard free energy of formation not equal to zero at 298 K?

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If a chemical reaction is exothermic but not spontaneous,which of the following must be true?

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For a reaction,ΔrH° = -208.8 kJ and ΔrS° = -308.2 J/K.At what temperature will ΔrG° = 0.00 kJ?

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Calculate ΔrG° for the reaction below at 425 °C, 2 HI(g) H2(g) + I2(g) ; K = 0.018.(R = 8.314 J/K⋅mol)

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ΔG° = 0 for a reaction indicates that _____.

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For the reaction Br₂(l) → 2Br(g) ,_____.

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At what temperatures will a reaction be spontaneous if Δ_rH° = +62.4 kJ and Δ_rS° = +301 J/K?

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For the reaction given below,ΔH⁰ = −1516 kJ at 25°C and ΔS⁰ = −432.8 J/K at 25°C.This reaction is spontaneous _____. SiH₄(g) + 2 O₂(g) → SiO₂(s) + 2 H₂O

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What is the equilibrium constant for reaction below at 25 °C? (R = 8.314 J/K⋅mol) 2 NO(g) + O₂(g) 2 NO₂(g) ; Δ_fG° [NO(g) ] = +86.6 kJ/mol and Δ_fG° [NO₂(g) ] = +51.2 kJ/mol.

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Using the given data,determine ΔrG° at 500.0 K for the reaction below. Ba(s) + H₂O(g) → BaO(s) + H₂(g) Substance Δ_fH°(kJ/mol-rxn) at 298 K S° (J/K·mol-rxn) at 298 K Ba(s) 0 62) 8 H₂O(g) -241.8 188) 7 BaO(s) -592 70) 4 H₂(g) 0 130) 6

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For a reaction,Δ_rH° = -208.8 kJ and Δ_rS° = -308.2 J/K.At what temperature will Δ_rG° = 0.00 kJ?

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Calculate Δ_rG° for the reaction below at 425 °C, 2 HI(g) H₂(g) + I₂(g) ; K = 0.018.(R = 8.314 J/K⋅mol)

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